As used herein, the term smart valve means a computer-controlled valve with a locally disposed microprocessor or chip programmed for adaptively responding to changing conditions. Known smart valve systems and remote safety logic solvers can be configured to be connected to a central monitoring computer system; however, such a configuration for use in a chemical or petroleum processing facility incurs significant overhead costs due to the requirement for communication links among the distributed mechanisms, such as safety devices. Those overhead costs are compounded since these smart valve systems and remote safety logic solvers are separate entities, but both are used for EIV control.
Prior art smart valve systems include an integrated assembly of an EIV, an actuator, a solenoid valve, a smart valve controller, a local control panel, and a plant-wide Emergency Shutdown (ESD) system. Each smart valve system uses the smart valve controller to control the travel of the EIV during routine functional testing, but relies heavily on the hard-wired input/output channels of a plant-wide ESD system for the logic required to provide local control through local control panels of individual smart valve devices and EIVs in the field.
Although some degree of local control of a safety instrumented function is provided by prior art systems, the implementation of local control throughout a plant-wide ESD system have been found to be very costly.
Prior art implementations of a set of local control actions for each EIV to complete safety instrumented functions for each specific application have also been found to be costly.
A need exists for integration of the logic required to perform local controls involved with a safety-instrumented function for each EIV in a smart valve controller to reduce the overall ESD input/output (I/O) requirements and to provide a significant cost savings, while implementing enhanced fault monitoring and detection.
Many systems are available in the prior art which monitor devices in the field and which provide diagnostic alarms upon detection of problems of such field-based devices. However, the such known systems require auxiliary computers to provide desired monitoring and diagnostic functionality. In addition, operators or maintenance technicians must use a stand-alone computer with special diagnostic software to interpret the data collected during an EIV function test and the associated test diagnostics.
Further, safety valve products of the prior art provide diagnostics remotely, but such products that are currently available for use in commercial processes and control systems do not include a local indicator mounted on the devices in the field, for performing such monitoring and diagnostic functions.
A need therefore exists for a device which simplifies operations for process plant operators and maintenance personnel by monitoring EIVs and their associated EIV control systems internally, as well as providing a local indicator to signal the existence of a detected problem when the problem is detected.
One drawback of known monitoring systems of the prior art is the overload of alarms; that is, the activation of too many alarms associated with numerous monitoring devices monitoring a large system or processing facility create personnel alert fatigue, which can pose a significant problem when a few serious hazardous conditions that produce alert or warning indications and alarms are scattered among other alert indications of less serious problems.
A need exists for a simple indicator to personnel of problems in a process system, such as an EIV, or a facility that personnel can readily recognize or identify as serious in order to take immediate action.
Known safety products and devices for monitoring faults can track the occurrence of faults, but none provide a running clock which track faults locally at the safety device. Accordingly, the lack of the ability to recognize and time-stamp faults reduces the accuracy of the tracking of faults.
A need exists for a locally positioned clock which tracks detected faults.
Known monitoring and detection systems provide limited alarm and warning capabilities. For example, U.S. Pat. No. 302,980 to Buell describes a fire extinguisher and alarm system using both local and remote central station alarm indications, but does not utilize or test EIVs using smart valve controllers.
U.S. Pat. Nos. 4,976,144 and 5,197,328 to Fitzgerald describe a diagnostic controller for testing and determining the operating condition of a pneumatically operated valve. However, the diagnostic controllers in Fitzgerald stroke a valve fully and thereby interrupt normal operations. The diagnostic controller also requires a portable external computer to be connected to pneumatic lines to collect data during testing.
U.S. Pat. No. 5,329,465 to Arcella et al. describes an on-line valve monitoring system which relies on a remotely located expert system to analyze valve data and to track and find trends in the historical data, but does not disclose a local diagnostic and indicator system.
U.S. Pat. No. 5,425,316 to Malone describes a control system used in a waste disposal system which has sensors for measuring conditions throughout the waste disposal system in order to improve the efficiency of waste incineration combustion chambers, as opposed to testing EIVs.
U.S. Pat. No. 5,573,032 to Lenz et al. describes a valve positioner with pressure feedback and other diagnostic functions, but the valve positioner lacks internal diagnostics and so there cannot be any local indication of detected faults.
U.S. Pat. No. 5,586,050 to Makel et al. describes a remotely controllable management system for a liquefied natural gas (LNG) station using both local and remote central station alarm indications. However, the management system relies on a remotely located host computer for emergency warnings and shut-down features. The management system does not describe EIVs and does not provide local fault indications based on internal diagnostics.
U.S. Pat. No. 5,684,451 to Seberger et al. describes a control system for digital communications with an instrument to perform diagnostic operations for use with an electro-pneumatic valve positioner, but does not suggest providing safety-related EIV on-board diagnostics and a local indicator for warning of detected failures.
U.S. Pat. No. 6,089,269 to Essam describes an emergency valve connected to a partial stroke controller to perform a partial stroke test at a predetermined time, but fails to provide any on-board diagnostics and any local indicator for detected failures.
U.S. Pat. No. 6,131,609 to Metso et al. describes a method and apparatus for surveying the condition of a control valve using on-board sensors, with diagnostics programmed into a digital positioner of the control valve. However, when faults are detected, such detection is communicated to a remote control system in a monitoring room in a separate control building, as opposed to providing a local indication warning of the detection of the faults.
U.S. Pat. No. 6,176,247 B1 to Winchcomb et al. describes a device for verifying the workability of a safety device, using on-board diagnostics of a safety related final element such as an EIV, and detected faults are communicated to a Remote Communications Interface (RCI), as distinguished from providing the local indication of a fault.
U.S. Pat. No. 6,283,138 B1 to Friend et al. describes a pressure relief valve monitoring device using both local and remote central station alarm indications to detect faults in pressure relief valves, as opposed to EIVs.
U.S. Pat. No. 6,435,022 B1 to Albuaijan, describes a partial stroke testing system using a limit switch invention to control the travel of a valve during on-line testing, but lacks on-board diagnostics and local indication of detected failures.
U.S. Pat. No. 6,631,882 B2 to Mack describes a testing apparatus to test a shutdown device during operation of a process, but requires use of a remotely located programmable logic controller to perform the testing and alarm functions on detection of test failure conditions. No on-board self-diagnostics are provided and there is no local indication of a detected fault.
U.S. Pat. No. 6,678,584 to Junk et al. describes a method and apparatus for performing diagnostics in a pneumatic control loop for a control valve, but lacks any provision of a local indication of detected dangerous faults.